In the Unit for Radio Communications, some of the research topics of the former Research Group for Radio Communications are still being pursued. Recently, particular emphasis is laid on the minimization of the required transmit power in MIMO mobile radio uplinks by pre-coding, and on the performance enhancement of the transmit amplifiers in OFDM systems by balancing the power efficiency against the distortions, which both increase, if the amplifier is driven more and more into the non-linear range of its characteristic.

As the crux of the mentioned transmit power reduction, each data content to be transmitted is represented by a selection of transmit signals representing the same information. Then, the one of these signals with the lowest transmit energy is radiated. Recent results of this work are presented in the doctoral thesis of F. Keskin, see Publications 2008.

The mentioned performance enhancement of the transmit amplifiers in OFDM systems relies on the application of Selective Data Mapping (SDM), Optimum Clipping (OC) and amplitude scaling of the OFDM symbols, and on power amplifiers based on the scheme Linear Amplification by Non-Linear Components(LINC).

• Introduction
• Air Interface Design by Transmitter Orientation and Receiver Orientation
• Interference Reduction in CDMA Mobile Radio Systems
• Joint Processing of received Signals in CDMA Mobile Radio Systems with Infinite and Quasi Infinite Data Transmission
• Transmit Array Processing for CDMA Downlinks
• Beyond 3G Mobile Radio Systems (JOINT)
• FLOWS
• MIMO Systems
• Channel Estimation
• Interference and Co-Existence in Mobile Radio Scenarios
• System Modeling and Simulation by ML-Designer
• Multi-Static and Synthetic Aperture Radar System
• Location of Radio Sources